I suspect that what you're looking for is an airfoil that has as broad a stall speed range as is possible. Some have quite a sharp peak at the point where separation takes place and the wing is considered to be stalled. Often these types of shapes are ones with fairly rearward max thickness points. The 6 digit NACA laminar flow airfoils are examples of this.

In the model world there's a few rules of thumb related to soft stalling airfoils. Well rounded leading edges, thick and max thickness points fairly close to the 25 to 30% marks. The NACA 0015 or 0018 and any of the cambered airfoils that use that shape are examples of very soft stalling airfoils. Something like a NACA 4415 could be pretty much guaranteed to have a very broad speed range from the initial mushiness to the final soft sort of stall.

On the other hand with thickness also comes some extra drag. But on a trainer where you don't want the model to suddenly pick up a lot of speed when the pilot puts the model into an inadvertent dive this is a good thing.

If this is what you're looking for then I suspect it would make a pretty nice trainer airfoil.